Wall board and plaster composition adapted thereto



J. A. LOCKHART.

WALL BOARD AND PLASTER COMPOSITIONUADAPTED THERETO.

APPLICATION FILED APR. 3, 192|.

Patented July 259 1922.,

JAMES A. @MAART LWEWTQR JAMES A. LOCKHART, 0F BUFFALO,A NEWvYORK,ASSIGNOR TO PITHO PLASTIC BOARD COMPANY, INC., OF BUFFALO, NEW YORK, ACORPORATION OF NEW YORK.

Masses.

Specification of Letters Patent.

Patented July 25, 1922.

applicati@ mea April a, 1921. serial 1ra-459,737.

vide wall board which shall be very light in weight, which shall bewithout brittleness and which will not crack consequent to nailing,which shall be 'waterproof and fireproof, whose body shall besufficiently porous to produce good suction effects and whose surfaceshall be sufficiently rough to produce good keying effects in connectionwith the application of outside finishing material, such as Keene orPortland .cement or stucco,

and which shall be exceedingly cheap to manufacture.

In the accompanying drawing;

Figure l is an elevation of the wall board in accordance with theinvention, showing more particularly the rough surface thereof to whichthe finishing material is applied.

Figure 2 is a sectional View of the same, and

Figure 3 isa view showing the shredded wood fibres which constitute anessential ingredient of the wall board.

The ingredients of the composition are plaster of Paris, lime (stone orrefined) and. shredded wood fibres.

While the proportions of the composition are not absolute I have foundthat the best results are obtained by providing about three parts, byweight, o-f plaster of Paris for one part of lime, and by providing theshredded wood libres in a quantity slightly less, by weight, than theplaster of Paris.

The shredded wood fibres lare not tobe confounded with excelsior sawdust, paper pulp or any merely generically required fibrous filler.These shredded wood fibres have a definite and characteristic form and adefinite proportional relation to the fin?.

parted to the finished wall board.

B the term shredded wood fibres as use herewith and in the claims Irefer to wood fibres of .peculiar formation, that is to say fibres whichare from three-quarters of an inch toone and oneuarter of an inch inlength, more or le, an are quite coarse, somewhat irregular in theirform and for the most part of what might be called compound formation,that is to say several of the fibres running in the same generaldirection willbe somewhat loosely united as a cluster. As far aspractical the fibres are illustrated in Fig'. 3. They are, of course,light and flexible, although having sufficient coarseness and stiffness.

The inigbredients'are thoroughly mixed together, a r which thecomposition is compressed and formed into wall board in any suitable orknown manner, one surface of the board, however, being left rough orunfinished, as shown in Figures l and .2, and the other surface beingypreferably smooth. The rough surface cooperates with outside finishingmaterial such as cement or stucco and the smooth surface cooperates withinside finishing material such as paint, calcimine or wall paper.

For most industrial purposes Vthe finished Wall board should be about aquarter of an inch thick, the shredded wood fibres being several timesgreater in length than the thickness of the board. These fibres not onlyextend throughout the entire mass, functioning most effeotually as areinforcement, but also will be exposed along the surface of the boardand will produce the desired and requisite roughness of the surface towhich the finishing material is to be applied. As exposed along suchroughened surface the shredded wood fibres will exfend in all directionsin the general plane of such' surface and will also extend at variousangles to such plane. Thus the roughened surface is characterized byclosely associated ridges, projections and indentations of irregularform, proportion and extent by virtue of which good keying effects areproduced. c The fibres, by virtue of their body, i. e., ooarseness andclusteringf relative sti- `ness and irregularity of outline, while serv-This preserves a certain porosity throughout the mass which is notincompatible with good waterproof qualities but which has theadvantages, first of enabling the board to dry very quickly in course ofmanufacture, and second, of providing for eilicient suction effects Whenthe finishing material, Keene or Portland cement or stucco is applied.These suction effects in connection with the keying effects of theroughened Surfaceinsure a mos-t secure application of the finishingmaterial.

The shredded Wood fibres in addition to the advantages specified alsoeliminate any quality of brittleness or riability, and iusure that theWall board will not crack under nailing.

In addition to the material specified a small quantity of sand may beadded to give body but While this is preferred it is not at allnecessary. c Y

Having fully Claim:

1. Plaster composition for Wall board comprising plaster of Paris, limeand shredded Wood fibres.

-2. Plaster composition for Wall board described my invention, I'

comprising plaster of Paris, lime and shred` fibres being several timesbeing several times greater in length than the thickness of the board.

5. Wall board composed of a mixture of plaster of Paris and lime andshredded Wood fibres incorporated therein, the fibres being severaltimes greater in length than the thickness of the board and producing aroughened surface to which finishing m'aterial may be applied.

In testimony whereof I aiix my signature.

JAMESA. LOCKHART.

